2 /* Copyright 1998, 2011 by the Massachusetts Institute of Technology.
4 * Permission to use, copy, modify, and distribute this
5 * software and its documentation for any purpose and without
6 * fee is hereby granted, provided that the above copyright
7 * notice appear in all copies and that both that copyright
8 * notice and this permission notice appear in supporting
9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose. It is provided "as is"
14 * without express or implied warranty.
17 #include "ares_setup.h"
19 #ifdef HAVE_SYS_SOCKET_H
20 # include <sys/socket.h>
22 #ifdef HAVE_NETINET_IN_H
23 # include <netinet/in.h>
28 #ifdef HAVE_ARPA_INET_H
29 # include <arpa/inet.h>
31 #ifdef HAVE_ARPA_NAMESER_H
32 # include <arpa/nameser.h>
36 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
37 # include <arpa/nameser_compat.h>
49 #include "inet_net_pton.h"
51 #include "ares_platform.h"
52 #include "ares_nowarn.h"
53 #include "ares_private.h"
60 /* Arguments passed to ares_gethostbyname() */
63 ares_host_callback callback;
65 int sent_family; /* this family is what was is being used */
66 int want_family; /* this family is what is asked for in the API */
67 const char *remaining_lookups;
71 static void next_lookup(struct host_query *hquery, int status_code);
72 static void host_callback(void *arg, int status, int timeouts,
73 unsigned char *abuf, int alen);
74 static void end_hquery(struct host_query *hquery, int status,
75 struct hostent *host);
76 static int fake_hostent(const char *name, int family,
77 ares_host_callback callback, void *arg);
78 static int file_lookup(const char *name, int family, struct hostent **host);
79 static void sort_addresses(struct hostent *host,
80 const struct apattern *sortlist, int nsort);
81 static void sort6_addresses(struct hostent *host,
82 const struct apattern *sortlist, int nsort);
83 static int get_address_index(const struct in_addr *addr,
84 const struct apattern *sortlist, int nsort);
85 static int get6_address_index(const struct ares_in6_addr *addr,
86 const struct apattern *sortlist, int nsort);
88 void ares_gethostbyname(ares_channel channel, const char *name, int family,
89 ares_host_callback callback, void *arg)
91 struct host_query *hquery;
93 /* Right now we only know how to look up Internet addresses - and unspec
94 means try both basically. */
101 callback(arg, ARES_ENOTIMP, 0, NULL);
105 if (fake_hostent(name, family, callback, arg))
108 /* Allocate and fill in the host query structure. */
109 hquery = malloc(sizeof(struct host_query));
112 callback(arg, ARES_ENOMEM, 0, NULL);
115 hquery->channel = channel;
116 hquery->name = strdup(name);
117 hquery->want_family = family;
118 hquery->sent_family = -1; /* nothing is sent yet */
121 callback(arg, ARES_ENOMEM, 0, NULL);
124 hquery->callback = callback;
126 hquery->remaining_lookups = channel->lookups;
127 hquery->timeouts = 0;
129 /* Start performing lookups according to channel->lookups. */
130 next_lookup(hquery, ARES_ECONNREFUSED /* initial error code */);
133 static void next_lookup(struct host_query *hquery, int status_code)
136 struct hostent *host;
137 int status = status_code;
139 for (p = hquery->remaining_lookups; *p; p++)
145 hquery->remaining_lookups = p + 1;
146 if ((hquery->want_family == AF_INET6) ||
147 (hquery->want_family == AF_UNSPEC)) {
148 /* if inet6 or unspec, start out with AAAA */
149 hquery->sent_family = AF_INET6;
150 ares_search(hquery->channel, hquery->name, C_IN, T_AAAA,
151 host_callback, hquery);
154 hquery->sent_family = AF_INET;
155 ares_search(hquery->channel, hquery->name, C_IN, T_A,
156 host_callback, hquery);
161 /* Host file lookup */
162 status = file_lookup(hquery->name, hquery->want_family, &host);
164 /* this status check below previously checked for !ARES_ENOTFOUND,
165 but we should not assume that this single error code is the one
166 that can occur, as that is in fact no longer the case */
167 if (status == ARES_SUCCESS)
169 end_hquery(hquery, status, host);
172 status = status_code; /* Use original status code */
176 end_hquery(hquery, status, NULL);
179 static void host_callback(void *arg, int status, int timeouts,
180 unsigned char *abuf, int alen)
182 struct host_query *hquery = (struct host_query *) arg;
183 ares_channel channel = hquery->channel;
184 struct hostent *host = NULL;
186 hquery->timeouts += timeouts;
187 if (status == ARES_SUCCESS)
189 if (hquery->sent_family == AF_INET)
191 status = ares_parse_a_reply(abuf, alen, &host, NULL, NULL);
192 if (host && channel->nsort)
193 sort_addresses(host, channel->sortlist, channel->nsort);
195 else if (hquery->sent_family == AF_INET6)
197 status = ares_parse_aaaa_reply(abuf, alen, &host, NULL, NULL);
198 if ((status == ARES_ENODATA || status == ARES_EBADRESP) &&
199 hquery->want_family == AF_UNSPEC) {
200 /* The query returned something but either there were no AAAA
201 records (e.g. just CNAME) or the response was malformed. Try
202 looking up A instead. */
203 hquery->sent_family = AF_INET;
204 ares_search(hquery->channel, hquery->name, C_IN, T_A,
205 host_callback, hquery);
208 if (host && channel->nsort)
209 sort6_addresses(host, channel->sortlist, channel->nsort);
211 end_hquery(hquery, status, host);
213 else if ((status == ARES_ENODATA || status == ARES_EBADRESP ||
214 status == ARES_ETIMEOUT) && (hquery->sent_family == AF_INET6 &&
215 hquery->want_family == AF_UNSPEC))
217 /* The AAAA query yielded no useful result. Now look up an A instead. */
218 hquery->sent_family = AF_INET;
219 ares_search(hquery->channel, hquery->name, C_IN, T_A, host_callback,
222 else if (status == ARES_EDESTRUCTION)
223 end_hquery(hquery, status, NULL);
225 next_lookup(hquery, status);
228 static void end_hquery(struct host_query *hquery, int status,
229 struct hostent *host)
231 hquery->callback(hquery->arg, status, hquery->timeouts, host);
233 ares_free_hostent(host);
238 /* If the name looks like an IP address, fake up a host entry, end the
239 * query immediately, and return true. Otherwise return false.
241 static int fake_hostent(const char *name, int family,
242 ares_host_callback callback, void *arg)
244 struct hostent hostent;
245 char *aliases[1] = { NULL };
249 struct ares_in6_addr in6;
251 if (family == AF_INET || family == AF_INET6)
253 /* It only looks like an IP address if it's all numbers and dots. */
254 int numdots = 0, valid = 1;
256 for (p = name; *p; p++)
258 if (!ISDIGIT(*p) && *p != '.') {
261 } else if (*p == '.') {
266 /* if we don't have 3 dots, it is illegal
267 * (although inet_addr doesn't think so).
269 if (numdots != 3 || !valid)
272 result = ((in.s_addr = inet_addr(name)) == INADDR_NONE ? 0 : 1);
277 if (family == AF_INET6)
278 result = (ares_inet_pton(AF_INET6, name, &in6) < 1 ? 0 : 1);
283 if (family == AF_INET)
285 hostent.h_length = (int)sizeof(struct in_addr);
286 addrs[0] = (char *)∈
288 else if (family == AF_INET6)
290 hostent.h_length = (int)sizeof(struct ares_in6_addr);
291 addrs[0] = (char *)&in6;
293 /* Duplicate the name, to avoid a constness violation. */
294 hostent.h_name = strdup(name);
297 callback(arg, ARES_ENOMEM, 0, NULL);
301 /* Fill in the rest of the host structure and terminate the query. */
303 hostent.h_aliases = aliases;
304 hostent.h_addrtype = aresx_sitoss(family);
305 hostent.h_addr_list = addrs;
306 callback(arg, ARES_SUCCESS, 0, &hostent);
308 free((char *)(hostent.h_name));
312 /* This is an API method */
313 int ares_gethostbyname_file(ares_channel channel, const char *name,
314 int family, struct hostent **host)
318 /* We only take the channel to ensure that ares_init() been called. */
321 /* Anything will do, really. This seems fine, and is consistent with
322 other error cases. */
324 return ARES_ENOTFOUND;
327 /* Just chain to the internal implementation we use here; it's exactly
330 result = file_lookup(name, family, host);
331 if(result != ARES_SUCCESS)
333 /* We guarantee a NULL hostent on failure. */
339 static int file_lookup(const char *name, int family, struct hostent **host)
347 char PATH_HOSTS[MAX_PATH];
348 win_platform platform;
350 PATH_HOSTS[0] = '\0';
352 platform = ares__getplatform();
354 if (platform == WIN_NT) {
358 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ,
359 &hkeyHosts) == ERROR_SUCCESS)
361 DWORD dwLength = MAX_PATH;
362 RegQueryValueEx(hkeyHosts, DATABASEPATH, NULL, NULL, (LPBYTE)tmp,
364 ExpandEnvironmentStrings(tmp, PATH_HOSTS, MAX_PATH);
365 RegCloseKey(hkeyHosts);
368 else if (platform == WIN_9X)
369 GetWindowsDirectory(PATH_HOSTS, MAX_PATH);
371 return ARES_ENOTFOUND;
373 strcat(PATH_HOSTS, WIN_PATH_HOSTS);
375 #elif defined(WATT32)
376 extern const char *_w32_GetHostsFile (void);
377 const char *PATH_HOSTS = _w32_GetHostsFile();
380 return ARES_ENOTFOUND;
383 fp = fopen(PATH_HOSTS, "r");
391 return ARES_ENOTFOUND;
393 DEBUGF(fprintf(stderr, "fopen() failed with error: %d %s\n",
394 error, strerror(error)));
395 DEBUGF(fprintf(stderr, "Error opening file: %s\n",
401 while ((status = ares__get_hostent(fp, family, host)) == ARES_SUCCESS)
403 if (strcasecmp((*host)->h_name, name) == 0)
405 for (alias = (*host)->h_aliases; *alias; alias++)
407 if (strcasecmp(*alias, name) == 0)
412 ares_free_hostent(*host);
415 if (status == ARES_EOF)
416 status = ARES_ENOTFOUND;
417 if (status != ARES_SUCCESS)
422 static void sort_addresses(struct hostent *host,
423 const struct apattern *sortlist, int nsort)
425 struct in_addr a1, a2;
426 int i1, i2, ind1, ind2;
428 /* This is a simple insertion sort, not optimized at all. i1 walks
429 * through the address list, with the loop invariant that everything
430 * to the left of i1 is sorted. In the loop body, the value at i1 is moved
431 * back through the list (via i2) until it is in sorted order.
433 for (i1 = 0; host->h_addr_list[i1]; i1++)
435 memcpy(&a1, host->h_addr_list[i1], sizeof(struct in_addr));
436 ind1 = get_address_index(&a1, sortlist, nsort);
437 for (i2 = i1 - 1; i2 >= 0; i2--)
439 memcpy(&a2, host->h_addr_list[i2], sizeof(struct in_addr));
440 ind2 = get_address_index(&a2, sortlist, nsort);
443 memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct in_addr));
445 memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct in_addr));
449 /* Find the first entry in sortlist which matches addr. Return nsort
450 * if none of them match.
452 static int get_address_index(const struct in_addr *addr,
453 const struct apattern *sortlist,
458 for (i = 0; i < nsort; i++)
460 if (sortlist[i].family != AF_INET)
462 if (sortlist[i].type == PATTERN_MASK)
464 if ((addr->s_addr & sortlist[i].mask.addr4.s_addr)
465 == sortlist[i].addrV4.s_addr)
470 if (!ares_bitncmp(&addr->s_addr, &sortlist[i].addrV4.s_addr,
471 sortlist[i].mask.bits))
478 static void sort6_addresses(struct hostent *host,
479 const struct apattern *sortlist, int nsort)
481 struct ares_in6_addr a1, a2;
482 int i1, i2, ind1, ind2;
484 /* This is a simple insertion sort, not optimized at all. i1 walks
485 * through the address list, with the loop invariant that everything
486 * to the left of i1 is sorted. In the loop body, the value at i1 is moved
487 * back through the list (via i2) until it is in sorted order.
489 for (i1 = 0; host->h_addr_list[i1]; i1++)
491 memcpy(&a1, host->h_addr_list[i1], sizeof(struct ares_in6_addr));
492 ind1 = get6_address_index(&a1, sortlist, nsort);
493 for (i2 = i1 - 1; i2 >= 0; i2--)
495 memcpy(&a2, host->h_addr_list[i2], sizeof(struct ares_in6_addr));
496 ind2 = get6_address_index(&a2, sortlist, nsort);
499 memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct ares_in6_addr));
501 memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct ares_in6_addr));
505 /* Find the first entry in sortlist which matches addr. Return nsort
506 * if none of them match.
508 static int get6_address_index(const struct ares_in6_addr *addr,
509 const struct apattern *sortlist,
514 for (i = 0; i < nsort; i++)
516 if (sortlist[i].family != AF_INET6)
518 if (!ares_bitncmp(addr,
520 sortlist[i].mask.bits))